Mobile terminals routinely communicate within a licensed spectrum via networks supervised by various cellular operators. The licensed spectrum, however, has a finite capacity and may become somewhat scarce as the number of mobile terminals that are configured to communicate within the licensed spectrum increases at fairly dramatic rates. As the demands placed upon the licensed spectrum by the various mobile terminals begin to saturate the licensed spectrum, the mobile terminals may experience increasing levels of interference with the licensed spectrum potentially eventually becoming a bottleneck for such communications.
An increasing number of other network topologies are being integrated with cellular networks. These other network topologies include, for example, WiFi networks, ad hoc networks and various other local area networks. The terminals, either mobile or fixed, supported by these other network topologies may communicate with one another in an unlicensed spectrum, such as a licensed-exempt industrial scientific medical (ISM) radio band. The ISM radio band supports other non-cellular systems, such as Will systems operating in accordance with the IEEE 802.11 standard, ZigBee systems operating in accordance with the IEEE 802.15 standard, Bluetooth systems and universal serial bus (USE) wireless systems. In this regard, the ISM radio band may include the 2.4 GHz ISM band in which WiFi 802.11b and 802.11g systems operate and the 5 GHz ISM band in which WiFi 802.11a systems operate. Though cellular technologies have not generally been deployed in the ISM band, such deployment could be considered for local-area Long Term Evolution (LTE) cellular networks as long as they meet the regulatory requirements in country-specific ISM bands, e.g. Federal Communications Commission (FCC) in the United States. Another example of a license exempt band is TV White Space (TVWS), which has been investigated widely in the recent years due to the large available bandwidths at suitable frequencies for different radio applications. In the United States, the FCC has regulated licensed or license-exempt TV bands for the secondary-system applications, e.g., cellular, WiFi, WiMax, etc., on TV Band Devices (TVBD).
One example of the manner in which a mobile terminal may utilize a network other than the cellular network is provided by a dual-mode cellular terminal A dual-mode cellular terminal may utilize a cellular network and a non-cellular network, such as a WiFi network. Thus, a dual-mode cellular terminal may be configured to implement a WiFi-to-cellular handover and/or a cellular-to-WiFi handover. By way of example, a user may initially begin a voice over internet protocol (VoIP) call via a WiFi connection at the user's residence or office. This WiFi connection may be supported by a WiFi hotspot while the user remains within the building. As the user leaves the building, however, the call may be handed over from the WiFi connection to a cellular network. The handover process includes a number of sequential operations in order to effect the handover. In the foregoing example, the VOIP call may be initially set up via the WiFi network with the assistance of a session initiation protocol (SIP) client on the cellular terminal. Upon detecting that the WiFi signal has become weak, such as due to the departure of the user from the building or for any other reason, a handover may be initiated, in this regard, a cellular trans-receiver radio may be activated and the call may be set up in the cellular network. In this regard, registration and authentication may be established on the cellular network, along with a voice bearer path. A handover may then be made to the cellular network and the WiFi link may be dropped so as to complete the handover process. As evident from the foregoing example, a WiFi-to-cellular handover requires some level of integration in the application layer (such as the VoIP client), the control layer (such as an internet protocol (IP) multimedia system (IMS) core, a serving gateway, a mobility management entity (MME) or the like), the access layer (such as the public switched telephone network (PSTN), WiFi access point, cellular base station or the like) and the device (such as the WiFi modem and the cellular modem).
Another type of communication terminal that may operate in these other network topologies includes machines that are configured, for example, for wireless communications. In this regard, machines may be employed for various applications including for smart homes, smart metering, fleet management, remote healthcare, access network operation management, etc. These machines may communicate in accordance with machine type communications (MTC), also referred to as machine-to-machine (M2M) communications. In this regard, the local communication directly between machines may include M2M communication, communication in a cluster of machines, communication within a grid of local machines that each perform certain tasks and advanced machines acting as a gateway for a number of machines having lesser capabilities so as to facilitate network access for the machines and secondary usage of the cellular system spectrum.